Predicting What Comes Next: Exploring Sequences and Progressions Mind Map
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What is a Sequence?
highA sequence is an ordered list of numbers, objects, or quantities written according to a rule or pattern.
Always write the term position along with the term value when solving missing-term or nth-term questions.
Explicit (Direct) Rule for a Sequence
highAn explicit rule gives the value of any term directly using its position number n.
Before substituting, write what n means: n = required position number.
Recursive Rule
highA recursive rule defines each term of a sequence using one or more previous terms, along with a starting term.
In recursive questions, mention both the first term and the rule for getting the next term.
Arithmetic Progression — Definition
highAn arithmetic progression is a sequence in which the difference between every two consecutive terms is constant.
Check at least two consecutive differences before calling a sequence an AP.
Sum of First n Terms of an AP
highThe sum of the first n terms of an arithmetic progression is the total obtained by adding its first n terms.
Choose Sn = n/2 × (a + l) only when the last required term l is known or can be found correctly.
Geometric Progression — Definition
highA geometric progression is a sequence in which each term is obtained by multiplying the previous term by the same non-zero constant ratio.
To test a GP, divide consecutive terms: second by first, third by second, and so on.
Real-World Applications of Sequences
highReal-world applications of sequences use ordered patterns to model repeated changes in money, distance, growth, decay, arrangements, or daily-life quantities.
Underline the phrase showing change: fixed increase suggests AP; multiplied by the same factor suggests GP.
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